Bridge to the future

Article provided by Kathrein, originally published on THEANTENNA, The company magazine of KATHREIN-Werke KG - Issue 1/2014. Republished with the permission of Kathrein.

How Kathrein is revolutionising indoor and campus-wide mobile communications

Data traffic in mobile communications is exploding. Increasing numbers of mobile users and mobile connections combined with higher speeds are creating significant challenges for mobile network operators. Transmission rates and capacities must be constantly expanded. The volume of mobile data traffic is predicted to increase tenfold in the next four years. Forecasts say that by 2018 more than 15 exabytes will flood through global networks each month. This is a volume of data equivalent to one million terabyte disk drives. One of the biggest challenges faced by network operators is how to design data traffic within buildings to meet future demands.

More than three-quarters of mobile data communications is now accounted for by data traffic within buildings. Besides offices, stores and private households it also involves public places such as airports, railway stations and hotels. More efficient data communications solutions with higher capacities will be required if future demand is to be met. The new LTE wireless networking standard allows such high data rates and is being rolled out to radio masts around the world. However, there are increasing restrictions within buildings. For example, energy-efficient architecture uses special metal-coated windows to reflect sunlight. However, it is difficult if not impossible for radio signals to pass through such windows. Operators are turning to centralized radio access networks (centralized RAN, C-RAN) in order to solve the problems of network coverage and capacity. They allow the resources of macro-networks to be efficiently exploited. As a consequence, solutions are required that support this C-RAN approach at the micro-level. Today, distributed antenna systems (DAS) play an important role in mobile communications within buildings. An advantage of DAS is the possibility to transmit signals for several mobile network operators. Indoor DAS systems are already deployed in sports arenas and airports, for example when the building owners, users or system integrators have installed a single antenna system to support various wireless services.

DAS solutions are static

DAS solutions have, however, a significant disadvantage – they are static and provide no capacity to adapt network capacity to match changing requirements quickly and affordably. Since a complex coaxial cable structure with splitters and antennas needs to be installed, DAS requires capacity requirements to be forecast and hotspots to be determined two or three years in advance. The entire system has to be manually reconfigured, calibrated and adjusted if building utilisation changes because, for example, a business moves from one floor to another or because higher bandwidth is required for mobile communications in the management board's offices. This results ina time-consuming and costly process that also demands a high level of expertise. In addition, capacity in a building is not used consistently over the course of time. The demand for data communications is different in a shopping centre than in offices or residential buildings. And a DAS tree structure must be duplicated in order for MIMO (multiple input and multiple output) to be supported for increased data rates on mobiles phones. This means high levels of investment and interruptions to operations. Innovative solution for maximum flexibility

With this in mind, Kathrein has developed a micro C-RAN solution that ensures that future demands can be met as data requirements in mobile communications constantly rise. "K-BOW" was launched at the Mobile World Congress in Barcelona in February 2014. The system uses the flexibility of a mobile communications pool and can make capacity available dynamically in areas of buildings in which it is actually needed. This allows mobile communications providers to tailor their networks to customer requirements within buildings and to respond quickly to changes in user behaviour. K-BOW aggregates data traffic with a centralised RAN platform and forwards multiple combinations of traffic signals to individual radio units (RUs). The solution is remotely-controlled over a network monitoring system so that capacity in any area within the building can be easily increased or decreased. Kathrein thus allows for the creation of self-organising networks (SONs) in buildings. LTE MIMO is also integrated with K-BOW, which can be introduced directly to offer end users the same data rates they find outside the building. K-BOW results in numerous benefits for mobile communications providers. They can implement their independent single- or multipleoperator strategy based on a single platform that is compatible with every solution for OEM base stations. Automatic calibration means that no costly system configuration is required by installation teams. No local access is required when adding new carrier frequencies or introducing MIMO, either. All operations can be performed by the network monitoring centre.

 Energy-saving potential

Shared network utilisation cuts the costs of investment for the providers involved. K-BOW supports multi-operator connectivity and provides the possibility of assigning specific signals from one mobile communications network operator to individual sectors in certain areas of a building. Selected bands and carrier frequencies can be enabled and disabled for each small cell sector. Using this function, mobile communications providers can, for example, activate a 2,100 MHz base signal to ensure basic network coverage within a building overnight and deactivate all other repeaters for the small cells. This function achieves energy savings of up to 50 per cent. K-BOW thereby opens up a whole new business model. At peak times, the lead operator can sell surplus or neutral host capacities and services to other operators.

The best signal – at all times

"The mobile communications sector will continue to experience dynamic change in the coming years. Our K-BOW system is setting the standard for mobile data transmission in buildings by simultaneously overcoming multiple technological challenges," says Dr Michael Weber, CTO at Kathrein. "We provide network operators with the flexibility they need to respond rapidly to their customers’ demands. We are opening up exciting new possibilities for indoor network optimisation, providing users with the best possible signal quality at all times."

K-BOW comprises a C-hub that is connected via provider-independent interfaces to the base stations of the operators and that covers all frequency bands. Since the entire spectrum of a band is supported, several operators as well as MIMO-capable base stations can be combined in the C-hub. The C-hub converts the signals into a robust digital stream of data. The digital transmission cable supports distances of up to 20 kilometres to the extension hub (E-hub), where the signals are allocated to sectors that can be modified via remote maintenance. That is also where remote units (RUs) are connected by coaxial cables or optical fibre. Each RU is equipped with several band-selective transceivers and LTE MIMO transceivers. In addition, the RUs also provide transparent IP connectivity with data throughput of up to 700 Mbit/s, which can be used for a sensor network, a small cell or wireless access points. RUs will be available with various levels of performance and offer mobile communications providers variable options with which they can roll out capacity in buildings as well as in open spaces and other outdoor areas.

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